Microelectronic devices are generally formed on a semiconductor wafer or other type substrate or workpiece. In a typical manufacturing process, one or more thin metal layers are formed on a wafer to produce microelectronic devices and/or to provide conducting lines between devices.
The metal layers are generally applied to the wafers via electrochemical plating in an electroplating processor. A typical electroplating processor includes a vessel for holding an electrolyte or plating liquid, one or more anodes in the vessel in contact with the plating liquid, and a head having a contact ring with multiple electrical contact fingers that touch the wafer. The front surface of the workpiece is immersed in the plating liquid and an electrical field causes metal ions in the plating liquid to plate out onto the wafer, forming a metal layer. Generally multiple electroplating processors are provided within an enclosure, along with other types of processors, to form an electroplating system.
The electrical contacts on the contact ring require frequent maintenance for cleaning and/or deplating. A so-called dry contact electroplating processor uses a seal to keep the plating liquid away from the contacts. The seal also requires frequent cleaning. The need to maintain the contacts and the seal reduces the throughput or use efficiency of the electroplating processor, as the electroplating processor is idle during the cleaning procedures. New processing systems overcome this drawback by processing wafers using a contact ring which is built into a chuck assembly which moves through the electroplating system with the wafer, and is not part of the processor. Therefore, contact ring maintenance can be performed in another location of the system, leaving the processor available to continue plating operations. The chuck assembly, however, must be precisely aligned with the processor, and must also securely engage the wafer, both mechanically and electrically. Accordingly, improved designs are needed.